This invention relates to hindered ortho-alkylated phenyl phosphonites which are effective in stabilizing organic materials particularly plastics, polymers and resins as well as mineral and synthetic fluids and oils.
Organic polymeric materials such as plastics, resins, lubricating and mineral and synthetic oils are subject to thermal, oxidative and photodegradation. A great variety of stabilizers are known in the art for stabilizing various substrates. Their effectiveness varies depending on the causes of degradation and the substrate stabilized. It is known that many stabilizers that are very effective long term antioxidants are relatively poor process stabilizers which require stabilization of the substrate, against thermal degradation for a short time, but at a relatively high temperature. Many stabilizers are relatively incompatible with the substrates which causes problems during the life of a product and lessens the stabilizer's effectiveness. Some stabilizers are either too volatile or thermally or hydrolytically unstable to be practical as commercial stabilizers.
In Japanese No. 73/41,009 (CA, 81, 121856 g (1974)), a non-hindered phenylphosphonite and a non-hindered phenylthiophosphonite are disclosed as heat stabilizers for ABS, PVC, polyolefins and other polymeric substances.
Diphenylphosphonites, diphenylene bis-phosphonites and terphenylene bis-phosphonites are described in U.S. Pat. No. 3,825,629 as stabilizers for organic materials. These compounds are structurally different from the instant compounds especially in reference to the diphenyl or terphenyl moiety directly attached to the P atom in these molecules.
Thermostabilized linear polyesters containing small amounts of diphenyl phenylphosphonite are claimed in U.S. Pat. No. 3,609,118. This patent contains a very broad generic reference to phenylphosphonites with no subgeneric disclosures and with only diphenyl phenylphosphonite being exemplified.
U.S. Pat. No. 3,809,676 and U.S. Pat. No. 3,978,020 disclose generically some phosphonites of structures related to those of the instant invention, but do not exemplify or specifically mention the hindered phosphonites of this invention. These references respectively pertain to thermally stable flame retardant polycarbonates containing a phosphonite or phosphinite in combination with a barium, calcium or cerium alkanoate or carbonate and to thermally stable polycarbonates containing a phosphonite and an epoxide compound.
The instant phosphonites exhibit surprisingly effective stabilization activity in a variety of substrates and are superior to previously known phosphonites in this stabilization efficacy. The superior performance of the instant phosphonites is particularly evident in those compositions where the effect of water or hydrolysis conditions is minimal.